The field of this invention is "oral compositions" which term is used herein to designate products which in the ordinary course of usage are retained in the oral cavity for a time and in a manner sufficient to contact essentially all of the dental surfaces, but are not intentionally ingested. Such products include, for example, dentifrices, mouthwashes, prophylaxis pastes and topical solutions.
The bis-biguanide antibacterial agents such as chlorhexidine, 1,6 bis(N.sup.5 -p-chlorophenyl-N.sup.1 -biguanido)hexane, are known to be effective antiplaque agents, but it has been recognized that they have a tendency to produce severe staining of the teeth. Haefele; U.S. Pat. No. 3,934,002; issued Jan. 20, 1976 and Haefele; U.S. Pat. No. 4,025,616; issued May 24, 1977, disclose the use of the insoluble salts of the bis-biguanides in oral compositions as a means of reducing the stain problem. Haefele; U.S. Pat. No. 3,937,807; issued Feb. 10, 1976; U.S. patent application Ser. No. 681,867, filed Apr. 29, 1976 and U.S. patent application Ser. No. 817,076, filed July 18, 1977, disclose the use of metal ion chelator compounds, such as amino acids, aminopolycarboxylates and hydroxypyrones, with the bis-biguanides to reduce stain.